SELMER, Tenn. – A preacher's wife accused of murdering her husband testified Wednesday that she doesn't remember picking up the shotgun or pointing it at her husband, but she said she did not pull the trigger. She heard a "boom" as the shotgun fired, she said.

Prosecutor Walt Freeland asked her if she understood what a trigger did, or which end of a shotgun was dangerous.

"You know that pulling a trigger is what makes it go boom?" Freeland asked.

"Yes, sir," Winkler replied.

She also said under cross-examination that her husband, Matthew, had done "nothing" for which he deserved to die.

Mary Winkler said she just wanted to talk to him when she went into their bedroom at the church parsonage, but she was terrified. He was physically and sexually abusive, she said.

That day, she just wanted to stop him from being so mean, she said.

After the gun fired, she ran from the house, she said. "I thought Matthew would be mad at me, and I didn't know what he would do to me."

Later, she returned to their bedroom and found him on his back, dead. A forensic pathologist testified that Matthew Winkler had been shot in the back.

Mary Winkler said that despite the abuse, she still loved her husband. She said she was ashamed about the abuse and didn't tell anyone.

"I didn't want anybody to know about Matthew," she said.

Her depiction of her marriage contrasts radically with the description by the prosecution, whose witnesses described Matthew Winkler as a good father and husband.

Matthew Winkler, 31, was found fatally shot in the parsonage where the family lived in March 2006. A day later, his wife was arrested on the Alabama coast 340 miles away, driving the family minivan with her three young daughters inside.

Earlier Wednesday, Mary Winkler testified her husband punched and kicked her, forced her to have sex she considered unnatural and refused to grant her a divorce.

The defense showed the jury a pair of white platform-heel shoes and a wig she said her husband wanted her to wear during sex.

Mary Winkler, 33, talked quietly, her eyes downcast as she described their sex life. She said her husband wanted her to look at pornography before sex, and photos she identified as coming from her husband's computer were entered as evidence.

She testified that he once kicked her in the face, and hit her, pushed her down and hit her with a belt. Shortly after they were married, "he just got me down and told me that I was his wife and we were family now, and he just screamed and hollered," she testified.

"I just wanted out," she said.

If convicted of first-degree murder, she could be sentenced to up to 60 years in prison. But a psychologist testified she could not have formed the intent to commit a crime because of her compromised mental condition.

Dr. Lynn Zager testified that Mary Winkler suffered from mild depression and post-traumatic stress disorder, which started at age 13 when her sister died and was worsened by her husband's abuse. The disorder made it more likely that Mary Winkler would have "dissociative episodes" in which she lost track of her ability to think and feel, Zager said.

The defense has said Mary Winkler intended to hold her husband at gunpoint only to force him to talk about the incident involving their 1-year-old daughter, Breanna, and that the shooting was accidental. She testified that her husband had put his hand over Breanna's nose and mouth to make the baby stop crying.

Several witnesses for the prosecution said they never saw any sign that Matthew Winkler was abusive. The couple's 9-year-old daughter, Patricia, testified that she had a good father and she never saw him mistreat her mother.

Last week, prosecutors played an audiotape in which Mary Winkler acknowledged shooting her husband, telling investigators her "ugly came out." She told authorities that her husband criticized her constantly and that she got tired of it and just "snapped."